While in one of our previous articles we talked about the fascinating organization of the Roman army, the strength of the Roman legion was also complemented by its incredibly deep yet sufficiently straightforward command structure. In other words, the hierarchical system of command was tailored to suit both ways, with overlapping representations that mirrored the interests of the senate, the aristocracy and most importantly – the rank-and-file soldiers (legionaries). In essence, it was a collective scope of leadership that fueled the tactical maneuvers (and even strategic deployment) of a legion – and this complex ambit is presented in a comprehensible manner by Historia Civilis’ amazing short animation on the command structure of the Roman legion.

Note* – The animation showcases the scope of post Marian reforms – a military system overhaul that only took place after 107 BC (thus corresponding to the late Roman Republic and the subsequent Roman Empire).

The ‘Other’ Units –

The video mentions the other units that completed the full century (hundred men) of Roman soldiers, thus comprising around 20 men. These units mainly included the slaves (or calones) who were attached to a legion. In fact they were governed as a part of the legion, with groups of 120 men attached to each cohort of 480 soldiers. So basically, a single legion (generally comprising ten cohorts) could be accompanied by around 1,200 slaves; and these men were trained for specific tasks. During times of emergency, they were even armed with weapons to defend their camps.

There were also soldiers who truly made a Roman military unit self-sufficient, and they were called the immunes, a group of highly trained specialists attached to each legion. Ranging from doctors, engineers to architects, these men were exempt from the hard labor duties of the rank-and-file soldiers, while also earning more than them.

Bonding And Dining Units –

The video makes it very clear that a contubernium was the smallest division in a Roman army. Now beyond discipline and training, one of the crucial reasons for the effectiveness of a legionary was directly related to his sense of fraternity within a century (made of 80 fighting men). So on a deeper level, a century (centuria) was further divided into ten contubernium (a ‘tent group’, each consisting of eight members). Such classifications basically led to an behavioral aspect of comradeship among the tent group who fought, dined and rested together in their military careers spanning over decades. This sense of identification often translated to high morale and protectiveness on the part of the legionaries when fighting in an actual battleground.

Interestingly, the bonding exercises were not just limited to the contubernium. The Roman army also had a system of rontubernium, which basically entailed a mess group. These grouped soldiers were expected to cook their own meals and eat them together (while the cost of food was deducted from their salaries). Simply put, the absence of mess halls and catering services rather solidified the bond between the legionaries who had to depend on each other even for peaceful meals.

The Vexillationes –

Credit: Artist Jason Juta / Copyright : Karwansary Publishers

While Roman legions fighting with their full capacity was a regular occurrence during early 2nd century AD, by the middle of 3rd century the conflicts faced by the Roman empire (and the changing emperors) were pretty volatile from both the geographical and logistical scope. And so it was uncommon and rather impractical for the entire legion to leave its provincial base to fight a ‘distant’ war on the shifting frontiers of 3rd century AD. As a solution, the Roman military commanders sanctioned the use of vexillationes – detachments from individual legions that could be easily transferred without compromising the core strength of a legion (which was needed for fortifying and policing its ‘native’ province).

These mobile combat ‘divisions’, comprising one or two cohorts, were usually tasked with handling the smaller enemy forces, while being also used for garrisoning duties along strategic points like roads, bridges and forts. And on rare occasions when the Romans were faced by large number of opposing troops, many of these different vexillationes were combined to form a bigger field army.

The Comitatus –

The later Roman empire and its volatile political scope also brought forth newer Roman units separate from the Roman legion. For example, Emperor Gallienus (who ruled alone from 260 to 268 AD) created his own mobile field army consisting of special detachments from the praetorians, legio II Parthica and other guard units. Hailed as the comitatus (retinue), this central reserve force functioned under the emperor’s direct command, thus hinting at the ambit of insecurities faced by the Roman rulers and elites during the ‘Crisis of the Third Century’. Interestingly enough, many of ‘extra’ equites (cavalry) that were assigned to each conventional legion, were also inducted as the elite promoti cavalry in the already opulent (and the militarily capable) scope of the comitatus.

Video Source: Historia Civilis (YouTube)

Book References: The Roman Army from Caesar to Trajan (By Michael Simkins) / Imperial Roman Legionary AD 161-284 (By Ross Cowan) / Arms and Armour of the Imperial Roman Soldier: From Marius to Commodus, 112 BC-AD 192 (By Raffaele D’Amato)